6.4. Common Forces http://www.ck12.org
Gravity and Normal Force Example
Question: A woman of mass 70.0 kg weighs herself in an elevator.
a) If she wants to weigh less, should she weigh herself when accelerating upward or downward? b) When the
elevator is not accelerating, what does the scale read (i.e., what is the normal force that the scale exerts on the
woman)? c) When the elevator is accelerating upward at 2.00 m/s^2 , what does the scale read?Answera) If she wants to weigh less, she has to decrease her force (her weight is the force) on the scale. We will
use the equation
F=ma